The invention relates to a front face of an electronics card, to an electronics card designed to be inserted into a housing, and to a method of inserting such a card into such a housing and of extracting it therefrom.
It is known that it is possible to make housings in which electronics cards can be disposed side-by-side, such housings serving to constitute control or monitoring units for controlling or monitoring a variety of electrical equipment. Such a housing can be stationary or it can constitute a drawer, and, in general, its front face is provided with an opening through which the cards are inserted, while its back face is provided with connection means for co-operating with each of the cards.
In view of recent developments in the connection techniques used to connect cards, such techniques including xe2x80x9cCompact PCI busxe2x80x9d type devices or connectors designed to the IEC 1076-4-101 Standard, the forces required to put such cards in place in a corresponding housing or to remove them therefrom are large since such cards are difficult to move, in particular at the end of insertion or at the beginning of extraction.
To mitigate that drawback, it is known, e.g. from U.S. Pat. No. 5,504,656 that the bottom portion of the front face of an electronics card can be hinged to a device provided with lugs organized to penetrate into notches in a bar disposed on the edge of the opening in the housing. A drive arm makes it possible to pivot the device relative to the notches. That device takes up a large amount of space on the front face of the card and, when a plurality of cards are juxtaposed in a housing, the corresponding devices form a relatively voluminous set of parts, and their unit cost is high compared with the cost of the card. In particular, in order to integrate a drive device in each front face, it is necessary to make said front face in a plurality of portions, and to fit a plurality of accessory parts such as a pin and assembly screws, which is both complex and costly. Unfortunately, such a device must be installed on each of the cards, which increases by a corresponding amount the cost of a control or monitoring unit equipped with a plurality of cards. In addition, when the lugs are engaged in the notches of the bar, the device masks one of the screws for fixing the card to the housing, thereby giving rise to a risk of forgetting to tighten that screw on inserting the card, it then not being impossible for the card to slip relative to the housing. In particular, no direct inspection can be made by an operator to check that the screw for fixing the card is properly tightened. In addition, such a device reduces the accessible area on the font face of the card, which makes it impossible to use standardized connectors that comply with a DIN standard and that are of low cost, and to install a centering device making it possible to form an xe2x80x9cunpluggablexe2x80x9d drawer, as described in FR-A-2 743 977. Finally, such a device must be adapted as a function of the type of connectors used between the card and the back face of the housing, so that it can happen that the same housing is equipped with different types of front faces and different types of such devices, which makes the housing relatively complex to manage, in particular for performing maintenance on an electronics unit.
An object of the invention is more particularly to remedy those drawbacks by proposing a novel structure for the front face of an electronics card, making the card easy to insert and to extract without having to use a complex special device such as a device known from the prior art.
To this end, the invention provides a front face of an electronics card designed to be inserted into a housing through an opening, at least one of the edges of which opening is provided with a notched bar, wherein that portion of said front face which is to be disposed in the vicinity of said bar is provided with at least one abutment surface for abutting against a drive member engaged through one of said notches when inserting said card into said housing or when extracting it therefrom.
By means of the invention, it is possible to terminate the card-insertion movement or to start the card-extraction movement by bearing against the surface provided for this purpose so that said surface is subjected to a strong force directed towards or away from the back of the housing. The drive member may be dimensioned such that it makes it possible to displace the card without excessive force, in particular by means of leverage. No permanent drive member is provided on the front face, thereby considerably reducing the cost of such a front face. Finally, the front face of the invention may be made in one piece, which gives it good rigidity.
In advantageous aspects of the invention, the front face incorporates one or more of the following characteristics:
It has two abutment surfaces that slope in different directions about a longitudinal plane, one of said abutment surfaces being suitable for co-operating with said drive member for the purpose of inserting said card into said housing, the other surface being suitable for co-operating with said drive member for the purpose of extracting said card. In which case, said two abutment surfaces slope relative to each other at an angle lying in the range 60xc2x0 to 90xc2x0, and preferably about 70xc2x0. It is also possible to make provision for said abutment surfaces to be dimensioned and positioned relative to said front surface in a manner such that a common edge that is common to said abutment surfaces is disposed substantially facing the inside edge of a notch of said bar, when said card is installed in said housing. It is thus possible to insert the drive member through the notch to interact with one or other of its abutment surfaces, as a function of the desired direction of the force to be exerted on the front face and on the card.
The front face is provided with at least one abutment surface at each of its ends, namely its top end and its bottom end, which makes it possible to obtain the above-mentioned advantages at both edges of the opening in the housing when both of said edges are provided with notched bars.
The abutment surface is formed during molding of said front face. The front face is preferably made of Zamack (a zinc alloy) because this material offers good molding characteristics, good rigidity and good conductivity, even after nickel-plating. Thus, the marginal cost of such an abutment surface is zero because it is obtained without any extra cost relative to an operation of molding a state-of-the-art front face.
The abutment surface is provided slightly set back from a top edge or a bottom edge of said front face, in the thickness of said front face.
The invention also provides an electronics card designed to be put in place in a housing, and which is provided with a front face as described above. Such an electronics card is easier to handle than prior art electronics cards, while being more reliable and having a cost that is lower than cards equipped with devices such as the device known from U.S. Pat. No. 5,504,656.
The invention also provides a method of inserting an electronics card into a housing or of extracting it therefrom, an opening in the housing being provided with a notched bar. The method consists in inserting a drive member through one of the notches in said bar, in causing said member to bear against an abutment surface provided on a portion of the front face of said card, which portion is to be disposed in the vicinity of said bar, and in exerting a pivot force on said drive member to pivot it about its abutment zone via which it bears against an edge of said notch, so that a force is transmitted to said front face, at said abutment surface, in a direction corresponding to inserting said card or to extracting said card.
The method of the invention is particularly simple to implement because it is necessary merely to use a single drive member to put a plurality of cards in place successively in a housing or to extract a plurality of cards successively from a housing. The drive member is advantageously a screwdriver which, in any case, must be used to tighten or to loosen a fixing screw for fixing the card to the housing. Since leverage is used by pivoting or tilting the screwdriver about the zone via which it bears in the notch of the bar, a strong force can be transmitted to the front face, thereby making it possible to overcome opposing forces generated at the connection devices for connecting the card to the back face of the housing.